Feed for sewing machine

ABSTRACT

A sewing machine has a pair of superposed workpiece guides which conduct a pair of workpieces one atop the other to a stitching location with the edges of the workpieces lying directly over one another so that the machine can form a line of stitching parallel to the workpiece edges. A pair of rollers lying in a common plane inclined to the transport direction is provided immediately upstream of the stitching location and their plane intersects the guide edges downstream of these rollers, so that they exert a biasing force on the two workpieces toward the guide edges. The upper roller at least is displaceable transverse to the transport direction out of the path of the upper workpiece so as to allow loading of the machine.

United States Paten r 1 Nicolay et al..

1 1 FEED FOR SEWING MACHINE [75] Inventors: Karl Nicolay, Bielefeld;Karl Buschmann, Brackwede; Jesus Perez Madueno, Brake, all of Germany[73] Assignee: Durkoppwerke GmbH, Bielefeld,

Germany 221 Filed: Aug. 22, 1974 21 Appl. No.: 499,407

[30] Foreign Application Priority Data Aug. 22, 1973 Germany 2342305[52] US. Cl 112/153; 112/211 [51] Int. CL' D0513 35/10 [58] Field ofSearch 112/211, 214, 136, 148,

' [56] References Cited UNITED STATES PATENTS 2,971,483 2/1961 Cordier112/153 X 3,463,482 8/1969 Baron et al. 270/93 June 17, 1975 3,782,3101/1974 Stockel 112/153 3,815,530

6/1974 Denton 112/214 Primary Examiner-George V. Larkin Attorney, Agent,or Firm-Karl F. Ross; Herbert Dubno 57 i ABSTRACT A sewing machine has apair of superposed workpiece guides which conduct a pair of workpiecesone atop the other to a stitching location with the edges of theworkpieces lying directly over one another so that the machine can forma line of stitching parallel to the workpiece edges. A pair of rollerslying in a common plane inclined to the transport direction is providedimmediately upstream of the stitching location and their planeintersects the guide edges downstream of these rollers, so that theyexert a biasing force on the two workpieces toward the guide edges. Theupper roller at least is displaceable transverse to the transportdirection-out of the path of the upper workpiece so as to allow loadingof the machine.

10 Claims, 4 Drawing Figures PATENTEDJUN 17 ms FIG.2

SHEET PATENTEUJuu 17 [975 SHEET Emi FIIJI.

FEED FOR SEWING MACHINE FIELD OF THE INVENTION The present inventionrelates to a workpiece feed for a sewing machine. More particularly thisinvention concerns such a feed for a sewing machine adpated to stitchtogether a pair of overlying textile workpieces parallel to one of theedges thereof.

BACKGROUND OF THE INVENTION It is known to provide a sewing machine atthe stitching plate thereof with a pair of superposed laterally openingguides having guide edges which extend parallel to the stitchingdirection. A workpiece is introduced into each of these guides with itsedge running along the respective guide edge so that the machine canform a line of stitching parallel to the edges of the workpiece.Thereafter the two fabric edges can be over stitched with a zigzag orunited in a French or flat fell seam.

These workpiece guides are generally constituted by a stack of fourplates with the first and third plates up from the stitching plateforming the guide edges and the second and fourth plates serving to holddown and flatten the workpieces.

It is absolutely essential that the edges of the two workpieces remaincontinuously on contact with the guide edges. To this end it is known toform the stitching plate with a plurality of ridges which are inclinedin the transport direction toward the guide edges so as to urge thefabric workpieces toward these guide edges. It is also known to form abump or the like on the stitching plate to one side of the stitchinglocation so as similarly to bias the fabric toward the guide edges.

The principal difficulty with both of these arrangements is that theyare effective only on the lowermost workpiece, that is the workpiecelying directly on the surface of the stitching plate. A guide for theuppermost workpiece has been dispensed with because of the difficulty itwould create in setting up the machine.

OBJECTS OF THE INVENTION It is therefore an object of the presentinvention to provide an improved workpiece feed for a sewing machine.

Yet another object is the provision of such a feed for a machine adaptedto sew together of a pair of workpieces along a line parallel to theiredges.

A further object is to provide a workpiece feed for a sewing machinehaving a pair of laterally open guides next to a stitching plate with aguide edge in each of the guides extending parallel to the stitchingdirection.

Yet another object is the provision of such a feed which is effectiveboth on the upper workpiece and the lower workpiece, the terms upper andlower here merely referring to position relative to the stitching platewhich traditionally underlies the workpieces.

These objects are attained according to the present invention in asystem wherein a pair of rollers are provided as the feed means, one ofthese rollers engaging from above on the upper workpiece and the otherroller engaging from below on the lower workpiece. According to thepresent invention these rollers are rotatable about axes which areparallel to each other and inclined to the feed direction. The rollersare arranged upstream of the stitching location and lie generally inplanes which cross the stitching direction and intersect the guide edgesdownstream of the rollers so that these rollers exert a biasing effecton the workpiece toward the guide edges.

Such rollers need not be driven, in fact simple idler rollers functionadmirably to maintain the two workpieces snugly against their guideedges. The apparatus is simple in the extreme and effective on bothworkpieces.

In accordance with another feature of this invention the two rollers liedirectly opposite one another so that absent workpieces between themthey would engage each other. Means is provided for varying the pressurewhich the upper and/or lower roller exerts on the workpieces. Inaddition means is provided for varying the angle of attack of theserollers so as to alter the force which these idler rollers exert on theworkpiece perpendicular to the stitching direction.

In accordance with yet another feature of this invention meansisprovided for displacing the upper and/or lower roller laterally out ofthe way for loading of work pieces into the guides. This means cancomprise a slider on the stitching plate which is displaceableorthogonally to the stitching direction and which automatically liftsthe respective roller upwardly away from the work' piece as it isdisplaced laterally.

BRIEF DESCRIPTION OF THE DRAWING The above and other objects, featuresand advantages will become more readily apparent from the fc lowing,reference being made to the accomparym drawing in which:

FIG. 1 is a section through a sewing machine equipped with a feedaccording to the present invention in operative position;

FIG. 2 is a top view of the feed shown in FIG. 1;

FIG. 3 is a view similar to FIG. 2 illustrating the feed in inoperativeposition; and

FIG. 4 is a section taken along line IVIV of FIG. 3.

SPECIFIC DESCRIPTION As shown in FIGS. 1 and 2 a sewing machine has abase surface 1 on which is mounted an arm 2 carrying a verticallyreciprocal needle 3. The machine has a stitch plate 4 formed with aneedle hole 5 through which a feed foot 6 or the machine engages so asto define a transport direction D (FIG. 2).

A pair of superposed steel plates 7 and 8 have edges 7 and 8' whichextend parallel to the direction D adjacent the stitch plate 4 and curveback away from the direction D upstream of the plate 4. These two edges7' and 8' are vertically in line and form a guide edge 11 parallel todirection D. A pair of plates 9 and 10 separate the plates 7 and 8. Theplate 9 extends parallel to the base surface 1 across the stitchingdirection D so as to form a narrow gap adapted to receive a lowerworkpiece Nl. The plate 10 overlies the upper guide plate 8 like theplate 9 and again forms a gap adapted to receive a respective upperworkpiece N2.

A pair of smaller plates 12 and 13 lying in the same plane as the plates9 and 10, respectively extend up to the stitching location at thestitching plate 4.

A slide 14 secured to plates 12 and 13 and displaceable in a transversedirection T orthogonal to the direction D is carried on one end of anarm 16 operated by the piston rod of a small pneumatic cylinder 15. Theother end of this arm 16 is pivoted on a link 30 which itself is pivotedfixedly on the sewing machine. Thus extension of the cylinder pushes theslide 14 into the position illustrated in FIG. 2 and retraction of thiscylinder l5 pulls it back into the positionsof FIG. 3 and A rod 17 issecured at one end in a fork 31 pivotal about an axis a on the slide 14and is formed at its other end with a collar 26 in which is fitted acrank 18. A screw 32 secures the crank 18 fixedly in the socket 26. Theend of this crank 18 pivotally carries a roller 19 defining a rollerplane P and rotatable about an axis A orthogonal to the plane P andinclined to the direction D, intersecting the guide edge 11 upstream ofthe center of the roller 19. The surface of this roller 19 formed with aplurality of ridges and the roller 19 is freely rotatable on the end ofthe crank 18. A leaf spring 20 secured at one end of the slide 24 ispressed against the rod 17 by a set screw 21 threaded into an arm 22 onthe slide 14 and provided with a lock nut 23. Thus screwing theadjustment screw 21 in and out by means of its knurled head allows thespring force downwardly on the crank 18 and rod 17 to be varied.

The plate 13 is formed with an oval hole 27 in line with the roller 19.The slide 14 is displaceable in a base 24 provided with a ridge 25having a head engageable with the collar 26. Thus when the slide 14 ispulled back in the direction T away from the stitching station 4 theroller is pivoted up about axis a by engagement of the element 25 withthe collar 26.

In addition under the surface 1 and the stitching plate 4 there isprovided another roller 28 lying in the roller plane P and rotatable ona respective pivot rod 29 parallel to the axis A. A hole 33 (FIG. 3) isformed in the stitching plate 4 in order to permit this roller 28 toengage through the stitching plate 4 with the under workpiece N1.

In operation the cylinder 15 is first actuated to withdraw the slide 14and plate 13 back into the position of FIG. 3, automatically lifting theroller 19. A lower workpiece N1 is loaded between the surface 1 and theplates 9 and 12 and an upper workpiece is loaded between the plates 9and 12 on one side and 10 and 13 on the other side. The cylinder is thenactuated so as to displace the upper roller 19 back into the positionsof FIGS. 1 and 2 and thereby dropping this roller 19 down onto the upperworkpiece N2 so as to press it against the lower workpiece and press thelower workpiece against the lower roller 28. The stitching operation iscommenced and the workpieces rotate the rollers l9 and 28, therebyimparting to themselves a coefficient of force in the direction of arrowT toward the guide edge 11.

The surface of the rollers 19 and 28 is shown to be formed of aplurality of small ridges to aid in engagement with the workpieces N1and N2. It is also within the scope of this invention to provide theserollers with a friction coating such as a rubber layer. In addition theplates, 7, 8, 9, 12, and 13 are coated with polytetrofluorethylene, asynthetic-resin having a very low coefficient of friction. In particularthe edges 7' and 8' are so coated so as to reduce friction with theworkpieces. Such an arrangement has been found extremely effective forholding the workpieces against the guide edges of the sewing machine.This insures a line of stitching exactly parallel to the edges of theworkpieces without requiring constant close attention by the machineoperator.

We claim:

I. A workpiece feed for a sewing machine having a pair of laterally openguides provided on a stitching surface adjacent a stitching locationthereon and having a pair of guide edges offset from the stitchinglocation and parallel to the machine stitching direction, said feedcomprising:

a pair of rollers to either side of the stitching surface downstreamfrom said stitching location and each rotatable in a roller planeintercepting said guide edges downstream of said rollers; and

a pair of axles defining respective rotation axes transverse to saiddirection supporting said rollers.

2. The feed defined in claim 1 further comprising means for displacingone of said rollers and the respective axis transverse to saiddirection.

3. The feed defined in claim 2 further comprising means for pressingsaid one roller down toward said surface.

4. The feed defined in claim 3, wherein said rollers both lie in thesame roller plane.

5. The feed defined in claim 4, wherein each of said rollers is providedwith a friction surface engageable with said workpieces.

6. The feed defined in claim 4 wherein said surface is formed with ahole, the other of said rollers engaging through said hole with one ofsaid workpieces and said one roller engaging the other workpiece.

7. The feed defined in claim 4, further comprising means for liftingsaid one roller away from said surface on displacement thereoftransverse to said stitching direction away from said location.

8. The feed defined in claim 7, further comprising means for displacingsaid plane relative to said direction.

9. The feed defined in claim 8 wherein said means comprises a crankconstituting said axle and a socket receiving said crank, wherebyrotation of said crank in said socket displaces said plane relative tosaid direction.

10. The apparatus defined in claim 6, wherein said guides include astack of plates, two of which are formed with said edges and two ofwhich extend transverse to said direction across the pass of saidworkpieces, the uppermost of the latter two plates being formed with aholethrough which said one roller is engageable with the respectiveworkpiece.

1. A workpiece feed for a sewing machine having a pair of laterally openguides provided on a stitching surface adjacent a stitching locationthereon and having a pair of guide edges offset from the stitchinglocation and parallel to the machine stitching direction, said feedcomprising: a pair of rollers to either side of the stitching surfacedownstream from said stitching location and each rotatable in a rollerplane intercepting said guide edges downstream of said rollers; and apair of axles defining respective rotation axes transverse to saiddirection supporting said rollers.
 2. The feed defined in claim 1further comprising meAns for displacing one of said rollers and therespective axis transverse to said direction.
 3. The feed defined inclaim 2 further comprising means for pressing said one roller downtoward said surface.
 4. The feed defined in claim 3, wherein saidrollers both lie in the same roller plane.
 5. The feed defined in claim4, wherein each of said rollers is provided with a friction surfaceengageable with said workpieces.
 6. The feed defined in claim 4 whereinsaid surface is formed with a hole, the other of said rollers engagingthrough said hole with one of said workpieces and said one rollerengaging the other workpiece.
 7. The feed defined in claim 4, furthercomprising means for lifting said one roller away from said surface ondisplacement thereof transverse to said stitching direction away fromsaid location.
 8. The feed defined in claim 7, further comprising meansfor displacing said plane relative to said direction.
 9. The feeddefined in claim 8 wherein said means comprises a crank constitutingsaid axle and a socket receiving said crank, whereby rotation of saidcrank in said socket displaces said plane relative to said direction.10. The apparatus defined in claim 6, wherein said guides include astack of plates, two of which are formed with said edges and two ofwhich extend transverse to said direction across the pass of saidworkpieces, the uppermost of the latter two plates being formed with ahole through which said one roller is engageable with the respectiveworkpiece.